As previously mentioned, ReactOS is an open source clone of Microsoft's
Windows (NT based) operating systems that is still under development. It
natively implements the Win32 APIs and even attempts to be compatible with
Windows NT/2000/XP device drivers.

The ReactOS project has come a long way in the last few years, having
had to overcome a number of obstacles and difficulties. Currently things
are moving full steam ahead and the current release of ReactOS is looking
even more promising. Of course they could always use more help from the
community.

Things that are working now:

TCP/IP Networking

New ATA/SATA driver for better compatibility.

USB

A few things that are currently lacking:

Printing (That's the most important function of an operating system!)

Sound (although supposedly coming real soon now)

Integrated print/file sharing (like typing in \\myserv\share\myfile in
a file open box and have it automatically open the file)

Again, the desktop has not changed much. The file windows now look
slightly more like the Windows 98 explorer. By default it hides the drive
bar, and now uses flat toolbar buttons.

The help system still wants to download and use the Gecko HTML renderer,
but other than that no web browser is involved.

There is a new revision of the ReactOS Explorer in progress but it does
not yet run.

ReactOS has gained a number of accessories including a remote desktop
program, a WordPad clone, and a simple paint program.

ReactOS now has a default set of screen savers. Oooh, look at all the
glowing radioactive butterflies!

Of course it still comes with a couple of built in games, WineMine
and Solitaire.

Most notably it now comes with a Downloader utility that makes it easy
for users to download and install application software that is not part
of the ReactOS project.